What is the special grace attaching to the sacrament of Matrimony?
It is the grace of perfect conjugal harmony which inspires a true, lasting, and supernatural affection; it is of such nature that it is able to resist all that might compromise this affection, until death; at the same time this grace brings with it a generosity whereby shortcomings and trials are overcome as regards the children which by the blessing of God may be the fruit of this union; and to this effect that they do nothing whatsoever that may hinder the coming into the world of their children. Moreover, this grace helps the parents to watch over their children with jealous care so that they may be healthy and strong both in body and soul (XLIX 1-6).
Next - The Catechism of the Summa - Tertia Pars - XLIII. OF THE SACRAMENT OF MATRIMONY; OF ITS NATURE, IMPEDIMENTS, DUTIES; OF DIVORCE; OF SUBSEQUENT MARRIAGE; AND OF ESPOUSALS (I)